Contact Firm Feel
http://www.firmfeel.com/b_body_mopar_torsion_bars.html
They make an .820 drag racing torsion bar. If they are a little pricy then look for a 6 cylinder bar for an e-body. I don't think it would be a good idea to turn down a torsion bar. You would ruin the integrity of the properties of the bar itself and it would probably snap under load like coming down from a wheel stand. Just my two cents.